It is known to place a differential amplifier for measuring the voltage difference existing between the first input and the second input, whose output is digitized and hooked up to a digital input of the microcontroller. However, this device does not make it possible to measure in a satisfactory manner the signal delivered by the sensor in the case where the second ground exhibits a negative potential with respect to the first ground. Moreover, a differential amplifier is generally expensive.
The aim of the present invention is in particular to remedy these drawbacks.